The total heat energy released during the transition of 14.2 grams of liquid mercury at 25°C to solid mercury at its melting point is 0.29855 kJ, considering both cooling and phase change processes.
To calculate the heat energy released when 14.2 grams of liquid mercury at 25 degrees Celsius is converted to solid mercury at its melting point, we can use the formula: heat = m × ΔHvap, where m is the mass in grams and ΔHvap is the heat of vaporization.
However, since we are going from liquid to solid, we need to use the heat of fusion instead. The heat of fusion of mercury is 11.1 J/g.
First, we need to calculate the amount of heat required to cool the liquid mercury from 25 degrees Celsius to its melting point. Q1 = mcΔT, where m is the mass, c is the specific heat capacity (0.14 J/g·°C for mercury), and ΔT is the change in temperature. Q1 = (14.2 g)(0.14 J/g·°C)(25°C - -38.87°C) = 140.93 J.
Next, we calculate the amount of heat released during the phase change from liquid to solid. Q2 = mΔHfusion, where m is the mass and ΔHfusion is the heat of fusion. Q2 = (14.2 g)(11.1 J/g) = 157.62 J.
The total heat energy release is the sum of Q1 and Q2: QTotal = Q1 + Q2 = 140.93 J + 157.62 J = 298.55 J. To convert this to kJ, we divide by 1000: QTotal = 298.55 J / 1000 = 0.29855 kJ.